1. Field of the Invention
The present invention relates to a method for filling concave portions of a concavo-convex pattern which is used in the field of manufacturing of, for example, semiconductors and information recording media, and a method for manufacturing a magnetic recording medium having a recording layer of concavo-convex pattern.
2. Description of the Related Art
Conventionally, a method for filling concave portions of a concavo-convex pattern has been used widely, in which a filler for filling concave portions is deposited over the surface of an object to be processed having a concavo-convex pattern and an excess part of the filler above the surface are removed for flattening (for example, see National Publication of PCT application No. 2002-515647).
To take an example, in the field of manufacturing of a semiconductor product, such a filling method is used to implant an insulator into a predetermined pattern of grooves (concave portions) formed in the surface.
In the field of manufacturing of magnetic recording media including a hard disc, the use of such a filling method has also been expected because of the following circumstances. Magnetic recording media have been improved in areal density significantly through such improvements as finer magnetic particles for constituting the recording layers, material modifications, and finer head processing. Although further improvements in areal density are expected in the future, there have arisen problems including limitations on head processing, erroneous information recording onto tracks adjacent to a target track of recording due to spreading of a recording magnetic field, and crosstalk. The improvement of the areal density by conventional modification techniques is thus approaching its limit.
In the meantime, discrete track media and patterned media have been proposed as prospective magnetic recording media capable of further improvements in areal density (for example, see Japanese Patent Laid-Open Publication No. Hei 9-97419). The discrete track media are ones in which the magnetic recording layer is formed in a concavo-convex pattern and the recording elements are divided in the radial direction. The patterned media are ones in which the recording elements are divided in the radial and circumferential directions. In a hard disc and other magnetic recording media, surface flatness is of importance in order to stabilize the head flying height. It is thus expected to flatten the surface of the magnetic recording layer by filling a nonmagnetic filler into concave portions between the recording elements by using the filling method described above.
The filler can be deposited by using such deposition techniques as sputtering, CVD (Chemical Vapor Deposition), and IBD (Ion Beam Deposition).
Moreover, the flattening can be effected by using such a processing technique as CMP (Chemical Mechanical Polishing).
Nevertheless, CMP has the problem of requiring much time and cost for cleaning and the like in order to remove slurry. Besides, CMP is a wet process. This has produced the problem that CMP, when combined with dry processes such as the step of processing a concavo-convex pattern, can complicate object transportation with a drop in the efficiency of the entire manufacturing steps. That is, the use of CMP in the flattening step has caused the problem of lower production efficiency.